Ti600合金的高温变形本构关系

Constitutive Relationship of Ti600 Alloy for Hot Deformation

摘要:

采用GW-1200A型控制器配合高温加热炉在WDW-300电子万能试验机上通过等温压缩实验研究了Ti600合金在温度为25~800 ℃、应变速率为10-4和10-3 s-1条件下的热变形行为，获得了该合金在变形过程中的真应力-真应变曲线，建立了该合金的高温本构关系。结果表明：Ti600合金在较高的温度(600和800 ℃)下流变应力随应变速率增大而增大，在较低温度(25和300 ℃)时变化不太明显。在一定的应变率条件下，随着温度升高流变应力降低。考虑到Ti600合金在不同温度下的真应力-真应变曲线随温度变化的发展趋势，建立了修正的井上胜郎高温本构关系，与实验结果对比验证了模型是可靠的。通过扫描电镜（SEM）观察发现，在室温准静态压缩条件下Ti600合金的断裂形式以脆性断裂为主，同时在局部区域出现韧性断裂特征

Abstract:

The hot deformation behavior of Ti600 alloy at deformation temperatures ranging from 25 to 800 oC and strain rates of 10-4 and 10-3 s-1 was studied by isothermal compression on a WDW-300 electronic universal testing machine. GW-1200A controller and high-temperature furnace were used to provide an accurate temperature control and measurement during testing. The true stress-true strain curves of Ti600 alloy were obtained. The results show that the flow stress of Ti600 alloy does not change obviously with the increasing of strain rate at lower temperatures (25 and 300 oC), while it increases with the increasing of strain rate at higher temperatures (600 and 800 oC), and the flow stress decreases with the increasing of temperature at the same strain rate. Based on the experimental results of true stress-true strain curves of Ti600 alloy at different temperatures, a modified Inoue Katsuro constitutive model was established to explore the flow stress of Ti600 alloy at elevated temperatures. A good agreement between the model predictions and the experimental results is derived, which verifies the reliability of the model. The fracture mode of Ti600 alloy at room temperature after the quasi-static compression was analyzed using scanning electron microscopy (SEM) and results show that the alloy is mainly of brittle fracture with some ductile fracture in the local region of the fracture surface